23. You want to estimate the mean time college students spend on their phones each day. Assume the population standard deviation is 80 minutes.

a) Suppose that the estimate must be within 4 minute of the population mean. Determine the required sample size to construct a 99% confidence interval for the population mean.

b) Suppose that the estimate must be within 8 minutes of the population mean. Determine the required sample size to construct a 99% confidence interval for the population mean.

c) Is the difference between a and b a major or a minor difference?